*
 * <p>If your answers are:
 *
 * <ul>
 *   <li>(1) "no" and (2) "no", use {@link #forGraph(SuccessorsFunction)}.
 *   <li>(1) "yes" and (2) "yes", use {@link #forTree(SuccessorsFunction)}.
 *   <li>(1) "yes" and (2) "no", you can use either, but {@code forTree()} will be more efficient.
 *   <li>(1) "no" and (2) "yes", <b><i>neither will work</i></b>, but if you transform your node
 *       objects into a non-recursive form, you can use {@code forGraph()}.

  }

  public void testIsPresent_no() {
    assertFalse(Optional.absent().isPresent());
  }

  @SuppressWarnings("OptionalOfRedundantMethod") // Unit tests for Optional
  public void testIsPresent_yes() {
    assertTrue(Optional.of("training").isPresent());
  }

  public void testGet_absent() {
    Optional<String> optional = Optional.absent();
    try {
      optional.get();
      fail();

  /** Override to return "indexOf" or "lastIndexOf()" for use in failure messages. */
  protected abstract String getMethodName();

  @CollectionSize.Require(absent = ZERO)
  public void testFind_yes() {
    assertEquals(
        getMethodName() + "(firstElement) should return 0", 0, find(getOrderedElements().get(0)));
  }

  public void testFind_no() {

   * a bucket in another map.
   */
  boolean isReusable() {
    return true;
  }

  static class NonTerminalImmutableMapEntry<K, V> extends ImmutableMapEntry<K, V> {
    /*
     * Yes, we sometimes set nextInKeyBucket to null, even for this "non-terminal" entry. We don't
     * do that with a plain NonTerminalImmutableMapEntry, but we do it with the BiMap-specific

  }

  private static void assertActuallyTrims(ImmutableDoubleArray iia) {
    ImmutableDoubleArray trimmed = iia.trimmed();
    assertThat(trimmed).isNotSameInstanceAs(iia);

    // Yes, this is apparently how you check array equality in Truth
    assertThat(trimmed.toArray()).isEqualTo(iia.toArray());
  }

  private static void assertDoesntActuallyTrim(ImmutableDoubleArray iia) {

  /** Override to return "indexOf" or "lastIndexOf()" for use in failure messages. */
  protected abstract String getMethodName();

  @CollectionSize.Require(absent = ZERO)
  public void testFind_yes() {
    assertEquals(
        getMethodName() + "(firstElement) should return 0", 0, find(getOrderedElements().get(0)));
  }

  public void testFind_no() {

      List<Sink> sinks = Lists.newArrayList();
      for (int chunkSize = 4; chunkSize <= 32; chunkSize++) {
        for (int bufferSize = chunkSize; bufferSize <= chunkSize * 4; bufferSize += chunkSize) {
          // yes, that's a lot of sinks!
          sinks.add(new Sink(chunkSize, bufferSize));
          // For convenience, testing only with big endianness, to match DataOutputStream.

  }

  private static void assertActuallyTrims(ImmutableLongArray iia) {
    ImmutableLongArray trimmed = iia.trimmed();
    assertThat(trimmed).isNotSameInstanceAs(iia);

    // Yes, this is apparently how you check array equality in Truth
    assertThat(trimmed.toArray()).isEqualTo(iia.toArray());
  }

  private static void assertDoesntActuallyTrim(ImmutableLongArray iia) {

  }

  public void testIsPresent_no() {
    assertFalse(Optional.absent().isPresent());
  }

  @SuppressWarnings("OptionalOfRedundantMethod") // Unit tests for Optional
  public void testIsPresent_yes() {
    assertTrue(Optional.of("training").isPresent());
  }

  public void testGet_absent() {
    Optional<String> optional = Optional.absent();
    try {
      optional.get();
      fail();

      List<Sink> sinks = Lists.newArrayList();
      for (int chunkSize = 4; chunkSize <= 32; chunkSize++) {
        for (int bufferSize = chunkSize; bufferSize <= chunkSize * 4; bufferSize += chunkSize) {
          // yes, that's a lot of sinks!
          sinks.add(new Sink(chunkSize, bufferSize));
          // For convenience, testing only with big endianness, to match DataOutputStream.